1. Field of the Invention
The present invention generally relates to lithography processes employed in semiconductor device fabrication and, more particularly, the present invention relates to the formation of a patterned photoresist, and to a method of a patterning a surface layer of a semiconductor substrate using a patterned photoresist.
A claim of priority is made to Korean Patent Application No. 2002-0048129, filed Aug. 14, 2002, the contents of which are incorporated herein by reference in their entirety.
2. Description of the Related Art
As the integration density of semiconductor devices continues to increase and as chip sizes continue to decrease, there is an increasing need to form patterns with finer and finer dimensions. However, as the patterned dimensions in lateral directions are reduced as necessary to form fine patterns, it is also necessary to reduce the thickness of the photoresist layer in order to avoid the collapse of the resist pattern during a wet development process of lithography. This reduction in thickness of the resist layer undesirably deteriorates resistance to dry etching, and serious line edge roughness (LER) is often observed.
In an effort to overcome the poor resistance to dry etching, a method has been proposed for reducing the overall thickness of a silicon-containing resist layer using a bi-layer resist (BLR) structure. However, according to the BLR technique, adhesion to underlying layer materials is weak and solubility to a developer solution is relatively poor, making it difficult to achieve a high resolution.
U.S. Pat. No. 5,234,793 discloses a BLR technique which includes coating a liquid, silicon-containing compound on a resist pattern subjected to exposure and development. As a result, the dry etching resistance of the resist pattern is improved, and a pattern size can be reduced in the case of forming a hole pattern, e.g., trench or contact hole. However, this technique still has several limitations. That is, it is quite difficult to adjust a CD bias due to a difference in the amount of silicon-containing compound coated according to various pattern sizes and shapes. Also, this technique can only be applied when using a resist material which includes an anhydride group, but is not suitably used with KrF or ArF resist materials, which are commercially available at present. Further, coating a liquid compound on a resist pattern is disadvantageous in that it increases costs and extends production times.